Thermostatically controlled circuit controller



' March 27, 1934. o, A, oss 1,952,895

THERMOSTAT I CALL! CONTROLLED C IRCUI T CONTROLLER Filed Dec. 2, 1930 59 65.6: i 0 4 V l A QfNI iENER.

. ATTORNEYS.

Patented Mar -27, 1934 UNITED STATES THERMOSTATICALLY CONTROLLED CIRCUIT CONTROLLER Oscar A. Ross, New York, N; Y., assignor to General Plate Company, Attleboro, Mass., at corporation of Massachusetts Application December 2, 1930, Serial No. 499,428

6 Claims.

This invention refers to temperature controlled electric switches and more particularly to such switches as employed in conjunction with electric sadirons or similar heat application devices.

One object of this invention is the provision of a quick-acting, thermostatically controlled switch wherein contact pressure is maintained at substantially a maximum value until the actual separation of the contacts.

Another object of this invention is the provision of a quick-acting, thermostatically-com trolled switch wherein a single thermostatic element has both a temperature responsive portionand a non-temperature responsive portion, both of which portions control the pressure at the contacts and the making and breaking of contacts, thereby obtaining a comparatively more rapid separation of the contacts as well as a maximum pressure therebetween at the instant just prior to the time at which said contacts are actually separated.

Another object of this invention is the provision of a quick-acting, thermostatically controlled switch of the class described wherein a wiping action is had between the contacts as they are opened and closed.

Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawing, in which are illustrated several of various possible embodiments of the invention,

Fig. 1 is an axial section of a switch embodying one form of the invention;

Fig. 2 is an axial section similar to Fig.. 1 but showing a second embodiment of the invention;

Fig. 3 is also an axial section similar to Fig. 1 but showing a third embodiment of the invention; A

Fig. 4 is also an axial section similar to Fig. 1 but showing a fourth embodiment of the invention;

Fig. 5 is a bottom plan view of-the Fig. 4 embodiment (see line V--V of Fig. 4);

Fig. 6 is also an axial section similar to Fig. 1 but showing a fifth embodiment of the invention; and, v

Fig. 'l is a top plan view of a switch common to all of the previous embodiments, on which line I--I represents the approximate location of the sections comprising Figs. 1, 2, 3, 4, and 6.

Similar reference characters indicate corresponding parts throughout the several views of the drawing.

Referring now more particularly to Figs. 1 and '7, numeral 1 indicates a base member, preferably formed of an electrical conducting material. Circularly arranged bolts or the like 2 having contact faces or members 3 on their under side are mounted in the base 1, with suitable insulating material electrically isolating them from said base. A stud 70 (Fig. 7) provides means for establishing an external electrical connection to the base 1, while a wire '71 interconnects the bolts 2 to form a second external connection.

Centrally secured in the base 1 is a mounting post or supporting member 4. On the under side of the base 1 the member 4 is provided with annular shoulders 5 and 7, the shoulder 7 forming the termination of a cylindrical portion 6. The lower end of the post 4 is'threaded to receive nuts 8.

Clamped between the nuts 8 and the shoulder 7 is a thermostatic contact bridging member comprising a pillow-shaped or bowl-shaped, resilient, monometallic member 10 having a central opening 9 through which the post 4 passes, and an inwardly-turned upperedge or flange 11. Numeral 13 indicates a dished bimetallic or thermostatic disc of the general type shown in Spencer Patent 1,448,240, which has a central opening 14 providing an internal edge 12. The edge 12 is secured by rivets or the like to the flange 11 of resilient member 10. The central opening 14 of thermostatic member 13 is large enough so that said thermostatic member may freely move vertically on the cylindrical portion 6 of post 4, although opening 14 isnot large enough to permit the thermostatic element to pass over the shoulder 5. I

The thermostatic disc 13 has the property of abruptly, alternately assuming two different positions, each of relative stability, with the change of ambient temperature. As in this case the peripheral region of the disc 13 is the region of greatest mobility as the disc passes from one position of stability to another, contact members 15 are mounted'on said peripheral region in position to engage the contact members" 3 on base 1.

The resilient member 10 is tensioned in initial assembly sufliciently to press contacts 3 and 15 firmly together, thereby achieving good electrical contact.

The operation of this first embodiment is as follows: At a predetermined relatively cold temperature, the thermostatic member 13 is in its stable position as shown in full lines in Fig. 1, contacts 3 and 15 being engaged. The resilient member 10 is stressed so that its free end 11 is constrained downwardly whereby the inner edge 12 of said thermostatic member is held away from shoulder 5 of stud 4. -As the ambient temperature rises, said thermostatic member 13 tends to change its shape to its alternative stable position shown by the dotted lines. However, this movement is comparatively slight, and as said movement takes place, the inner portion 12 is pressed upwardly by the free end 11 of resilient member 10. In this manner firm contact pressure between contacts 3 and 15 is maintained. At a critical temperature, the thermostatic member abruptly changes its form to that shown in the dotted position. During the-first portion of this abrupt movement the contacts 3 and 15 are maintained in closed position due to the upward movement at the center of the disc 13 occasioned-by the resilient member 10 relieving its initial stress.

This upward movement is abruptly terminated when the internal edge 12 abuts shoulderb, after which the remaining portion of the self-actuated movement of disc 13 snaps the contacts 3 and 15 apart abruptly. At the instant that the inner edge 12 engages theshoulder 5, thethermostatic member 13 is moving at a comparatively rapid rate in changing its form from one shape to the other, and as a result the contacts 3 and 15 are quickly and abruptly separated. The abrupt separation minimizes arc formation.

When, now, the ambient temperature'falls, the thermostatic member 13 again abruptly changes its shape to the full line position'shown in Fig. 1, the contacts 3 and 15 first reengaging, after which the inner edge 12 of saidfmember 13 is pressed downwardly by shoulder 5, thereby restressing the free end 11 of resilient member 10. This movement of the inner edge 12 away from shoulder 5 also produces a rubbing or wiping action between the contacts 3- and 15 whereby better contacting therebetween is effected.

2 illustratesan embodiment wherein a somewhat difierent type of resilient means is provided. The base 1, contacts 3, and-mounting post 4 are similar to their analogous parts in the Fig. 1 embodiment. However, in Fig. 2 the post 4 is provided with but one annular shoulder 21.

. Clamped between the shoulder 21 and nuts 8 is a resilient metallic disc 23, which is normally flat, and which may desirably be of monometallic composition, comprising, for example, an extension portion of one of the metals of an outer bimetallic disc or portion 22. The thermostatic disc 22 is of the same general type as the'disc'l3 of Fig. l.

About the periphery 24 ofdisc 22 are .provided the contacts 15 in cooperating relationship to the contacts 3 on base 1.

when the parts of this embodiment are assembled, the resilient disc 23 is stressedor bowed downwardly, as indicated in Fig. 2,: and its reaction furnishes pressure'to hold the contacts 3 and 15 infirm engagement.

The Fig. 2 embodiment operates similarly to the Fig; 1 embodiment, in that modification shown in Fig. 2 is similar to the operation in that normally the contacts 3 and 15 are engaged as shown in the full line position. As the ambient temperature is increased the thermostatic portion 24 tends somewhat to change its shape tothe dotted position shown. However, the contacts 3 and 15 are maintained in closed position by the outer edge 23a of resilient portion 23 moving upwardly to relieve its initial stress, as the thermostatic portion 24 tends to flatten. When the temperature rises to a predetermined value said thermostatic portion 24 reaches a critical stage and abruptly reverses its curvature to shape shown by the dotted line position. During the reversal, the contacts 3 and 15 remain closed at first, and until the resilientportion 23 becomes substantially flat, whereupon said contacts separate rapidly. The thermostatic portion 24 at this time, is moving at a high speed, said contacts being thereby snapped apart in such a manner as to prevent arcing therebetween.

In the Fig. 3 embodiment, the relative position of the thermostatic and resilient portions are reversed. As in Fig. 2, the base 1, contacts 3, and post 4 are substantially the same as the analogous parts in Fig. 1. In Fig. 3, the post 4 is provided with a single shoulder 32. Clamped between the shoulder 32 and the nuts 8 is the central portion of a bimetallic or thermostatic disc 33, similar to the disc 13 of the Fig. 1 embodiment. To the periphery 40 of disc 33 is aflixed the periphery 39 of a resilient annulus 34, which is given a slight curvature, thus bringing it to a somewhat frustoconical shape. A second annulus 35, similar to the annulus 34, but reversed in position, is affixed at its inner periphery 36 to the inner periphery of annulus 34. The joint between the annuli 34 and 35 may be crimped as illustrated, or it may be welded, or made in any other suitable manner.

About the outer periphery of annulus 35, on its upper surface, are mounted the contacts 15 in suitable position to engage the contacts 3 on base 1.

This embodiment differs from prior embodiments in that, in this embodiment the thermostatic member is rigidly mounted and the resilient member carries the relatively movable contacts,'while in prior embodiments the resilient member was rigidly mounted and the thermostatic member carried the contacts. However, the operation of this embodiment is not dissimilar to the operation of said prior embodiments.

It will be understood that in assembly the resilient annuli 34 and 35, together comprising the resilient member" of this embodiment, are compressed somewhat to provide pressure between contacts 3 and 15.

The operation of the Fig. 3 embodiment is as follows:

Normally the contacts 3 and 15 are engaged, the thermostatic member 33 is positioned in the full line position shown, and the outer edges of members 34 and 35 are resiliently constrained toward each other. As the ambient temperature rises the outer edge 40 of thermostatic member 33 tendsto move slightly toward the dotted-line position. Simultaneously the outer edges of members 34 and 35, in relieving their initial compression, are separated substantially to the same extent that member 33 moves, thereby maintaining firm engagement between contacts 3 and 15. Upon a further predetermined rise. in the ambient temperature, member 33 abruptly changes its form to the dotted position shown. During the initial part of the abrupt change, contacts 3 and 15 remain in contact due to further separation of sition, whereupon said contacts are snapped apart rapidly by the rapid movement of member 33 in changing its form. In this manner arcing between the contacts is prevented. When now, the ambient temperature drops to a determined value, the thermostatic member 33 again abruptly changes its form to the normal or full line position, the contacts 3 and 15 engaging before the termination of theabrupt movement and the remainder of the abrupt movement resiliently re-.- constraining the outer edges of members 34 and 35 together, thus effecting pressure engagement between said contacts as well as producing a wiping action therebetween.

Figs. 4 and 5 illustrate a variation of the Fig. 1 embodiment of the invention, in which the resilient member 10 of Fig. 1 is replaced by a pair of rectangular plates 41 and 42, joined at their outer edges as at 43 by crimping, welding, or the like, and bent to form a full eliptical spring. The resilient means, while thus difiering from that of Fig. 1, still retains the characteristic pillow or bowl shape. The upper plate 41 has a central opening 44 registering with the opening 45 in thermostatic disc 13. The disc 13 and plate 41 are joined together about the openings 44 and 45 by rivets or the like. Openings 44 and 45 are both large enough to permit free movement on the cylindrical portion 6 of post 4. The lower plate 42 has a central opening 46 which receives the post 4 and provides means, with the shoulder 7 and nuts 8, for clamping plate 42 to the post 4. In assembly, the plates 41 and 42 are stressed in the same manner as the resilient member 10 in Fig. 1.

The operation of the modification shown in Figs. 4 and 5 is substantially the same as that described in connection with the modification shown in Fig. 1, the resilient members 41 and 42 acting to compensate for the initial slight movement of thermostatic member 13 due to the slight change in shape thereof, and thereby to maintain substantially maximum contact pressure both in the stable position and during the initial abrupt movement of said member in changing its shape.

Fig. 6 illustrates a variation of the Fig. 2 embodiment of the invention, in which the monometallic resilient portion 23 of Fig. 2, instead of being an extension of one of the metals of the bimetallic portion, is formed as an entirely separate disc 60, which is riveted or otherwise aflixed to the thermostatic er bimetallic portion 22 by rivets or the like 61. In other respects, Fig. 6 is the same as Fig. 2. The operation of the Fig. 6 variation is the same asthe operation of the Fig. 2 embodiment, and need not be recounted.

A common feature of all of the embodiments shown and described isthe provision, with a selfactuating thermostatic element having movable contacts associated therewith, of a resilient means which functions to press such movable contacts firmly against a set of cooperating fixed contacts when. said thermostatic element is in one of its stable positions and during a portion of its travel to its alternative stable position, thereby securing increased speed at the time of breaking contacts together with maximum contact pressure up to the instant of breaking.

These features, inhibiting arcing and sputtering, are of considerable value in the construction of switches of the type herein concerned.

In view of the above, itwill be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in carrying out the above constructions without'departing from the scope of the invention, it is intended that N all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting What I claim is:

1. A switch comprising a relatively stationary base member, at least one contact mounted on said base member, a post rigidly mounted onsaid base member, resilient means, and self-actuating thermostatic means, one of said means being mounted on said post and the other of said means being mounted on the aforesaid means, said thermostatic means comprising an element having two positions of relative stability and moving abruptly from one of said positions to another upon predetermined ambient temperature variation, and at least one contact supported on one of said means arranged to'cooperate with said first-named contact to control a circuit, said resilient means holding said contacts firmly pressed together when said thermostatic element is in one position of stability, and for a part of the abrupt motion of said thermostatic element from such position to its alternate position of stability.

2. A switch as set forth in claim 1 in which 106 the resilient means comprises a pillow-shaped spring.

3. A switch as set forth in claim 1 in which the resilient means comprises a pair of plates arrangedin pillow shape, one of said plates being 110 secured at its central region to said post, and the other of said plates being secured at its central region to the central region of said thermostatic element.

4. A switch comprising a relatively stationary base member, at least one contact mounted on said base member, a spring disc mounted upon said base member, a self-actuating thermostatic element mounted about the periphery of said spring disc, said thermostatic element having two positions of relative stability and moving abruptly from one of said positions to another upon predetermined ambient temperature variation, and at least one contact supported on said thermostatic element arranged to cooperate with said first-named contact to control a circuit, said spring disc holding said contacts firmly pressed together when said thermostatic element is in one position of stability, and for a part of the abrupt motion of said thermostatic element from such position to its alternate position of stability.

5. A switch as set forth in claim 1 in which the resilient means comprises a spring disc about the periphery of which the said thermostatic element is arranged, said spring disc being mounted at its center on said post.

6. A switch as set forth in claim 1 in which the resilient means comprises a spring disc mounted at its center on said post, and the thermostatic element comprises a bimetallic annulus secured along its inner periphery to the outer periphery of said spring disc.

OSCAR A. ROSS. 

